1. Field of the Invention
The present invention generally relates to a conductor connection structure in a conductor crimp portion of a crimp contact, and particularly relates to a crimp contact having a highly reliable conductor connection structure.
2. Description of the Prior Art
As shown in FIG. 4, conventionally, a crimp contact is constituted by a contact portion 1, a conductor crimp portion 2 continued from the contact portion 1, and a coating fastening portion 3 continued from the conductor crimp portion 2. In such a crimp contact, the conductor crimp portion 2 and the coating fastening portion 3 are formed in such a manner that opposite ends of a plate-like portion continued from the contact portion 1 are bent upward and end portions of the opposite ends are further curved inward so as to form grasping arms 2a and 3a so that spaces are formed, respectively, for accommodating wire conductors 4 plus a coating 5 over the wire conductors.
In this configuration of the crimp contact, the conductors 4 where the coating 5 has been removed and the conductors 4 where the coating 5 is left as it is are inserted into the conductor crimp portion 2 and the coating fastening portion 3, respectively, and the grasping arms 2a and 3a are fastened by use of a fastening tool so that the grasping arms 2a and 3a are plastically deformed to come into close contact with the conductors 4 and with the coating 5, respectively. Even after removal of the fastening force of the fastening tool, the grasping arms 2a and 3a are urged against the conductors 4 and the coating 5 by residual elastic force in the grasping arms 2a and 3a. respectively.
If the contact urging force of the grasping arm 2a against the conductors 4 is insufficient, the contact between the grasping arm 2a and the conductors 4 is insufficient so that the electric resistance between the conductor crimp portion 2 and the conductors 4 increases to thereby cause failures such as heat generation or burnout, or so that the contact is loosened or dropped out by an external force to thereby cause a maloperation or operation stoppage of equipment connected to the crimp contact. It is therefore necessary to strictly control the size of the conductor crimp portion 2.
Since each conductor 4 has a substantially circular section, air gaps 6 are produced between the conductor crimp portion 2 and the conductors 4 and between the adjacent conductors 4 so that an oxide film or the like is generated on the outer surfaces of the conductors 4 and on the inner surface of the conductor crimp portion 2. This increases the electric resistance between the conductors 4 and the conductor crimp portion 2 as time elapses to thereby cause a defective contact.
In order to prevent a defective contact from occurring, soldering is sometimes performed. In that case, however, the step of soldering constitutes an additional step. Also, the solder becomes hard and hence fragile, and even if no defective contact is created due to the soldering, when vibrations or the like are applied to the soldered portion, that portion may be easily disconnected.